Modulation of terahertz radiation

Abstract

A method of modulation terahertz radiation comprising: (A) generating Terahertz radiation by pumping nonequilibrium electrons into a Magnon Gain Medium (MGM), wherein propagation of nonequilibrium electrons in the MGM causes generation of nonequilibrium magnons, and wherein interaction between the nonequilibrium magnons causes generation of the Terahertz radiation; and (B) frequency modulating THz radiation generated in the MGM by applying longitudinal AC magnetic field, or by applying AC electrical field bias.

1. A method of modulation terahertz radiation comprising:
 (A) generating Terahertz radiation by pumping nonequilibrium electrons into MGM; wherein propagation of nonequilibrium electrons in said MGM causes into magnon gain medium (MGM); wherein propagation of nonequilibrium electrons in said MGM causes nonequilibrium magnons causes generation of said Terahertz radiation; and 
 (B) modulating said generated in said MGM Terahertz radiation. 
 
   
   
     2. The method of  claim 1 , wherein said step (A) further comprises:
 (A1) providing said MGM; and 
 (A2) pumping nonequilibrium electrons into said MGM by using an electron pumping means. 
 
   
   
     3. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 1) placing said MGM in a thermostat to maintain temperature of said MGM below a critical temperature. 
 
   
   
     4. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 2) providing said MGM; wherein said MGM includes a conduction (valence band) that splits into two subbands, and wherein said first subband is configured to be populated by electrons having spin up, and wherein said orientation of spin up is an orientation directed along a direction of a magnetization of said MGM; and wherein said second subband is configured to be populated by electrons having spin down, and wherein said orientation of spin down is an orientation directed opposite to said direction of said magnetization of said MGM. 
 
   
   
     5. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 3) providing said MGM; wherein said MGM includes said conduction (valence band) that splits into said two subbands, and wherein said first subband is configured to be populated by electrons having spin up; and wherein said second subband is configured to be populated by electrons having spin down; and wherein said two subbands with said spin up and said spin down are separated by an exchange gap. 
 
   
   
     6. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 4) providing said MGM; wherein said MGM includes said conduction (valence band) that splits into said two subbands, and wherein said first subband is configured to be populated by electrons having spin up; and wherein said second subband is configured to be populated by electrons having spin down; and wherein said two subbands with said spin up and said spin down are separated by said exchange gap; and wherein if the exchange energy is positive then the bottom of said subband with said spin up is located below a bottom of said subband with said spin down. 
 
   
   
     7. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 5) providing said MGM; wherein said MGM includes said conduction (valence band) that splits into said two subbands, and wherein said first subband is configured to be populated by electrons having spin up; and wherein said second subband is configured to be populated by electrons having spin down; and wherein said two subbands with said spin up and said spin down are separated by said exchange gap; and wherein if said exchange energy is positive then said bottom of said subband with said spin up is located below said bottom of said subband with said spin down; and if said gap Δ is much greater than the maximum of {T C , E f }, wherein T C  is the Curie temperature of said MGM, and wherein E f  is the Fermi energy of electrons, then only electron states in said lower subband with spin up are occupied in equilibrium, i.e. said electrons are fully polarized. 
 
   
   
     8. The method of  claim 2 , wherein said step (A1) further comprises:
 (A1, 6) providing said MGM; wherein said MGM includes said conduction (valence band) that splits into said two subbands, and wherein said first subband is configured to be populated by electrons having spin up; and wherein said second subband is configured to be populated by electrons having spin down; and wherein said two subbands with said spin up and said spin down are separated by said exchange gap; and wherein if said exchange energy is negative then said bottom of said subband with said spin up is located above said bottom of said subband with said spin down. 
 
   
   
     9. The method of  claim 1 , wherein said step (B) further comprises:
 (B1) modulating said Terahertz radiation generated in said MGM by placing said MGM into a AC magnetic field. 
 
   
   
     10. The method of  claim 1 , wherein said step (B) further comprises:
 (B2) frequency modulating said Terahertz radiation generated in said MGM by placing said MGM into a AC magnetic field. 
 
   
   
     11. The method of  claim 1 , wherein said step (B) further comprises:
 (B3) modulating said Terahertz radiation generated in said MGM by applying AC electric field to said MGM. 
 
   
   
     12. The method of  claim 1 , wherein said step (B) further comprises:
 (B4) frequency modulating said Terahertz radiation generated in said MGM by applying AC electric field to said MGM. 
 
   
   
     13. The claim of  9 , wherein said step (B1) further comprises:
 (B1, 1) applying a direct current (DC) magnetic field to tune the main frequency of said Terahertz radiation generated in said MGM. 
 
   
   
     14. The claim of  9 , wherein said step (B1) further comprises:
 (B1, 2) modulating fluctuations of a magnetic moment of said MGM by applying said AC magnetic field. 
 
   
   
     15. The claim of  11 , wherein said step (B3) further comprises:
 (B3, 1) applying a direct current (DC) magnetic field to tune the main frequency of said Terahertz radiation generated in said MGM. 
 
   
   
     16. The claim of  11 , wherein said step (B3) further comprises:
 (B3, 2) applying AC electric field to said MGM to modulate the concentration of electrons in said spin-down subband. 
 
   
   
     17. The claim of  11 , wherein said step (B3) further comprises:
 (B3, 3) applying AC electric field to said MGM to modulate the Fermi energy of said MGM. 
 
   
   
     18. The claim of  1  further comprising:
 (C) using said modulated THz radiation to transmit information in THz spectrum of frequencies. 
 
   
   
     19. The claim of  18 , wherein said step (C) further comprises:
 (C1) using said modulated THz radiation with modulating frequency up to 100 GHz to transmit information in THz spectrum of frequencies.